Chapter 10 - Hydrogen sulfide and reactive oxygen species crosstalk and acquisition of abiotic stress tolerance

Abstract

Hydrogen sulfide (H2S) was previously categorized as a toxic and environmentally hazardous gas. But in recent years, it has been considered to be a significant signaling molecule necessary for growth, development, and physiological processes of both plants and animals. Besides growth and development in plants, H2S has a major role in stress modulation responses along with senescence and maturation. H2S is considered to be ameliorative against various abiotic stresses like salinity, drought, heat, cold, and heavy metals. The direct role of H2S in scavenging reactive oxygen species (ROS) is little known, while the indirect impact of H2S on balancing ROS through antioxidative enzymes or signaling pathways is becoming well-known and further explored. Several studies have reflected that cysteine residues present in catalase, ascorbate peroxidase (APX), and dehydroascorbate reductase (DHAR) are vulnerable to oxidation by ROS. The involvement of sulfide in signaling pathways is reflected through protein persulfidation, where thiol of cysteine (−SH) is modified into persulfide (−SSH). Under stressful conditions in plants, cysteine thiols also undergo several modifications like S-sulfenylation (−SHO), S-glutathionylation (−SSG), and S-nitrosylation (−SNO). Later on, these persulfides are reduced back to thiols and involved in the normal functioning inside cells. Besides the antagonistic behavior of H2S and reactive oxygen species (ROS), a synergistic role has also been explored under various stress conditions in plants. Moreover, H2S and NO participate in mutual roles in the adaptation of oxidative stress during adverse environmental conditions. The interactive effects of H2S, ROS, and autophagy have demonstrated that sulfides are regulating autophagy in plant cells through persulfidation. Cooperation of H2S and H2O2 is being found to be beneficial for plants under various abiotic stresses. Therefore the present chapter highlights the generation and role of H2S in plants along with the crosstalk of H2S and ROS.